It has now been found that it is possible to use for cases for VRLA batteries polypropylene compositions with a particularly advantageous balance of properties, in particular of high rigidity and good impact resistance, by operating in two polymerization stages. In the first stage propylene is polymerized or copolymerized with minor amounts of comonomer(s), and in the second stage ethylene/α-olefin(s) mixtures are copolymerized in the presence of the propylene polymer obtained in the first step.